Self-retaining sutures having effective holding strength and tensile strength

ABSTRACT

A barbed suture with a first end and a second end and a body with a plurality of barbs extending from the body. Each barb causes the suture to resist movement in an opposite direction from which the barb faces. Projections extend from said suture. The projections can also engage tissue. The barbs cover the projections when the first end of the suture is moved in tissue and exposes the projections in order to engage tissue when the suture is moved in the direction of the second end through tissue.

CLAIM TO PRIORITY

This application is a continuation of U.S. application Ser. No.10/065,280, filed Sep. 30, 2002, now pending, which is incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

This invention relates, in general, to a barbed suture useful forconnecting bodily tissue in various surgical contexts, and moreparticularly, to the optimization of the disposition and/orconfiguration of the barbs on such barbed sutures.

TECHNICAL FIELD

Various surgical methods employing sutures have been used in the pastfor closing or binding together wounds in human or animal tissue, suchas skin, muscles, tendons, internal organs, nerves, blood vessels, andthe like. More specifically, the surgeon may use a surgical needle withan attached conventional suture (which can be a smooth monofilament orcan be a multi-filament) to pierce the tissue alternately on opposingfaces of the wound and thus sew the wound closed. Whether the wound isaccidental or surgical, loop stitching is the method often used,especially for surface wounds. The surgical needle is then removed andthe ends of the suture are tied, typically with at least three overhandthrows to form a knot.

As is well known, conventional sutures can be of non-absorbable materialsuch as silk, nylon, polyester, polypropylene, or cotton, or can be ofbio-absorbable material such as glycolic acid polymers and copolymers orlactic acid polymers and copolymers.

Since the time of their conception, barbed sutures, which are generallyof the same materials as conventional sutures, have offered numerousadvantages over closing wounds with conventional sutures. A barbedsuture includes an elongated body that has one or more spaced barbs,which project from the body surface along the body length. The barbs arearranged to allow passage of the barbed suture in one direction throughtissue but resist movement of the barbed suture in the oppositedirection. Thus, the main advantage of barbed sutures has been theprovision of a non-slip attribute. Accordingly, barbed sutures do nothave to be knotted, like conventional sutures. Like a conventionalsuture, a barbed suture may be inserted into tissue using a surgicalneedle.

For instance, U.S. Pat. No. 3,123,077 to Alcamo describes an elongatedcord for sewing human flesh, where the cord has a body portion andsharp-edged, resilient barbs projecting from the body at acute anglesrelative to the body. The barbed suture can be passed through tissue inone direction, but resists movement in the opposite direction.

Sutures with barbs disposed in a bidirectional arrangement, also calleddouble-armed sutures, are shown in U.S. Pat. No. 5,931,855 to Buncke andU.S. Pat. No. 6,241,747 to Ruff. More particularly, the suture has barbsfacing toward one end of the suture for about half the suture length andbarbs facing in the opposite direction toward the other end of thesuture for the other half of the suture length. This arrangement allowsthe barbs to move in the same direction as each respective suture end isinserted into the first and second sides of a wound. Such bi-directionalbarbed sutures not only are especially suitable for closing wounds withedges prone to separation, but also obviate the need to secure sutureends together with knotted loops.

Of interest is European Published Patent Application No. 1,075,843 A1 toSulamanidze and Mikhailov, published Feb. 2, 2001, derived fromPCT/RU99/00263 (published as WO 00/51658 on Sep. 8, 2000), priority toRU 991 03732 (Mar. 3, 1999), which shows conical barbs arrangedsequentially along the length of a thread and oriented in a directionopposite to that of the thread tension, with the distance between barbsbeing not less than 1.5 times the thread diameter.

Also of interest is U.S. Pat. No. 5,342,376 to Ruff. This patent showsan insertion device that is useful for positioning a barbed suture inorder to close a wound. The insertion device has a tubular body forreceiving a barbed suture, and preferably also has a handle tofacilitate manipulation of the device by the surgeon. The insertiondevice is recommended for use with a barbed suture where the sutureportion being inserted includes barbs facing a direction opposed to thedirection of insertion. Such sutures with barbs opposing the directionof insertion are also shown in '376 to Ruff.

The disclosures of all patents and patent applications mentioned hereare incorporated by reference.

Escarpment of barbs into a monofilament, depending on the barb cutdepth, reduces the straight pull tensile strength since the effectivesuture diameter is decreased. However, the straight pull tensilestrength of a barbed suture should be compared to the minimum knot pullstrength of a conventional suture (a non-barbed suture) in accordancewith the United States Pharmacopoeia since failure of conventionalsutures (which have to be knotted and must meet a minimum knot pulltensile strength) occurs most frequently at the knot due to increasedlocal stress.

To optimize the performance of a barbed suture, it is advantageous toconsider varying the barb geometry (barb cut angle, barb cut depth, barbcut length, barb cut distance, etc.) and/or the spatial arrangement ofthe barbs. This should not only enhance the tensile strength of a barbedsuture, but also should enhance the ability of a barbed suture inholding and maintaining wound edges together. Unlike conventionalsutures, which place tensions directly at the knots, barbed sutures canspread out the tension along the escarped suture length, often evenlyalong the length. Optimizing the disposition and/or the configuration ofthe barbs should therefore further increase the effectiveness of the newbarbed suture in maximizing the holding strength and minimizing the gapformation along the wound edges. The latter is particularly beneficialfor promoting wound healing.

Also, such new barbed sutures should approximate tissue quickly withappropriate tension, alleviate distortion of tissue, and help tominimize scarring, due to the self-retaining benefits imparted by thebarbs. The new barbed sutures would be especially useful in surgerieswhere minimization of scarring is imperative, such as cosmetic surgery,as well as in surgeries where space is limited, such as endoscopicsurgery or microsurgery.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a barbed suture forconnecting human or animal tissue. The barbed suture comprises anelongated body having a first end and a second end. The barbed suturefurther comprises a plurality of barbs projecting from the body. Eachbarb is adapted for enabling the barbed suture to resist movement, whenin tissue, in the direction that is opposite from the direction in whichthat barb faces. The barbed suture further comprises the barbs beingdisposed on the body in a disposition selected from a staggereddisposition, a twist cut multiple spiral disposition, an overlappingdisposition, a random disposition, or combinations thereof.

For the staggered disposition, the twist cut multiple spiraldisposition, and/or the overlapping disposition, the barbs may all befacing toward only one of the first and second ends. Alternatively, thebarbed suture may have at least a first portion and a second portion,where the barbs of the first portion are facing toward the first end andthe barbs of the second portion are facing toward the second end.

Also, in an alternative embodiment, the present invention provides abarbed suture for connecting human or animal tissue, where the suturecomprises an elongated body having a first end and a second end. Thesuture further comprises a plurality of barbs projecting from the body.Each barb is adapted for enabling the suture to resist movement, whenthe suture is in tissue, in the direction that is opposite from thedirection in which that barb faces. The suture further comprises thebarbs having a configuration selected from a barb cut angle θ rangingfrom about 140 degrees to about 175 degrees, a barb cut depth with aratio of cut depth to suture diameter ranging from about 0.05 to about0.6, a barb cut length with a ratio of cut length to suture diameterranging from about 0.2 to about 2, a barb cut distance with a ratio ofcut distance to suture diameter ranging from about 0.1 to about 6, acorrugated underside, an arcuate base, varying sizes, or combinationsthereof.

For the twist cut multiple spiral disposition, the barbed suturepreferably has a spirality α angle ranging from about 5 degrees to about25 degrees.

For the overlapping disposition, it is meant that at least two adjacentbarbs are disposed where one overlaps the other. During escarpment ofthe barbs, the overlapping is created by a barb (i.e., the overlappingbarb) being escarped into the topside of another adjacent barb (i.e.,the overlapped barb), and so on. Hence, part of the topside of theoverlapped barb becomes part of the underside of the overlapping barb,and so on. Thus, with the overlapping disposition, the barb cut distancebetween the overlapping barb and the overlapped barb may be shorter thanthe barb cut length of overlapped second barb, whereas, in general forbarbed sutures, the barb cut distance between two barbs≧the barb cutlength.

In still another embodiment, the present invention provides a barbedsuture for connecting human or animal tissue in combination with asurgical needle, where the combination comprises a barbed sutureattached to a surgical needle. The suture comprises a plurality of barbsprojecting from an elongated body having a first end and a second end.Each barb is adapted for enabling the suture to resist movement, whenthe suture is in tissue, in the direction that is opposite from thedirection in which that barb faces. The ratio of the surgical needlediameter to the suture diameter preferably is about 3:1 or less.Suitably, any of the inventive barbed sutures described here may beattached to a surgical needle.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a side view of one embodiment of the present invention,showing a barbed suture with barbs disposed in a 180 degree staggeredspacing;

FIG. 1B is a sectional view along line 1B-1B of the barbed suture inFIG. 1A;

FIG. 2A is a side view of another embodiment of the present invention,showing a barbed suture that is bi-directional with barbs disposed in a180 degree staggered spacing;

FIG. 2B is a sectional view along line 2B-2B of the barbed suture inFIG. 2A;

FIG. 3A is a side view of another embodiment of the present invention,showing a barbed suture with barbs disposed in a 120 degree staggeredspacing;

FIG. 3B is a sectional view along line 3B-3B of the barbed suture inFIG. 3A;

FIG. 4A is a side view of another embodiment of the present invention,showing a barbed suture that is bidirectional with barbs disposed in a120 degree staggered spacing;

FIG. 4B is a sectional view along line 4B-4B of the barbed suture inFIG. 4A;

FIG. 5A is a side view of another embodiment of the present invention,showing a barbed suture with barbs disposed in a twist cut multiplespiral disposition;

FIG. 5B is a sectional view along line 5B-5B of the barbed suture inFIG. 5A;

FIG. 6A is a side view of another embodiment of the present invention,showing a barbed suture that is bidirectional with barbs disposed in atwist cut multiple spiral disposition;

FIG. 6B is a sectional view along line 6B-6B of the barbed suture inFIG. 6A;

FIG. 7A is a sectional side view of a barbed suture, which isbidirectional with barbs disposed in a twist cut multiple spiraldisposition like the barbed suture in FIG. 6A, but illustrated in anenlarged section;

FIG. 7B is the sectional side view as illustrated in FIG. 7A, butrotated and clamped to align the barbs for measurement of the cutdistance between the barbs;

FIG. 8 is a side view of another embodiment of the present invention,showing a barbed suture with barbs in a random disposition;

FIG. 9 is a sectional side view of another embodiment of the presentinvention, showing a barbed suture having a barb with a corrugated orserrated underside;

FIG. 10A is a sectional perspective view another embodiment of thepresent invention, showing a barbed suture having a barb with an arcuatebase;

FIG. 10B is a sectional top plan view of the barbed suture in FIG. 10A;

FIG. 10C is a cross-sectional view along line 10C-10C of FIG. 10B;

FIG. 10D is a cross-sectional view along line 10D-10D of FIG. 10B;

FIG. 11 is a sectional side view of another embodiment of the presentinvention, showing a barbed suture with barbs of various sizes;

FIG. 12A is a sectional perspective view of another embodiment of thepresent invention, showing a barbed suture with barbs in an overlappingdisposition;

FIG. 12B is a perspective view of a portion of the overlapping barbs ofthe suture of FIG. 12A;

FIG. 12C is a plan view of the portion of barbs of FIG. 12B;

FIG. 12D is a side view along line 12D-12D of FIG. 12C; and

FIGS. 13A, 13B, 13C, and 13D show various surgical needles, where abarbed suture is attached to each surgical needle.

DETAILED DESCRIPTION

As used here, the term wound means a surgical incision, cut, laceration,severed tissue or accidental wound in human or animal skin or otherhuman or animal bodily tissue, or other condition in a human or animalwhere suturing, stapling, or the use of another tissue connecting devicemay be required.

Also as used here, the term tissue includes, but is not limited to,tissues such as skin, fat, fascia, bone, muscle, organs, nerves, orblood vessels, or fibrous tissues such as tendons or ligaments.

Moreover, the term polymer as used here generally includes, but is notlimited to, homopolymers, copolymers (such as block, graft, random andalternating copolymers), terpolymers, et cetera, and blends andmodifications thereof Furthermore, the term polymer shall include allpossible structures of the material. These structures include, but arenot limited to, isotactic, syndiotactic, and random symmetries.

Although the sutures are described below in a preferred embodiment witha circular cross section, the sutures could also have a non-circularcross sectional shape that could increase the surface area andfacilitate the formation of the barbs. Other cross sectional shapes mayinclude, but are not limited to, oval, triangle, square, parallelepiped,trapezoid, rhomboid, pentagon, hexagon, cruciform, and the like.Typically, barbs are cut into a polymeric filament that has been formedby extrusion using a die with a circular cross section, and thus, thecross section of the filament will be circular, as that is what resultsduring such extrusion. However, extrusion dies can be custom made withany desired cross-sectional shape.

Hence, the term diameter as used here is intended to mean the transverselength of the cross section, regardless of whether the cross section iscircular or some other shape.

Suitable diameters for the inventive sutures described below may rangefrom about 0.001 mm to about 1 mm, and of course, the diameter may befrom about 0.01 mm to about 0.9 mm, or from about 0.01 5 mm to about 0.8mm The typical diameter ranges from about 0.01 mm to about 0.5 mm. Thelength of the suture can vary depending on several factors such as thelength and/or depth of the wound to be closed, the type of tissue to bejoined, the location of the wound, and the like. Typical suture lengthsrange from about 1 cm to about 30 cm, more particularly from about 2 cmto about 22 cm.

The terms staggered and staggering as used here in relation to thedisposition of barbs on a suture are intended to mean that the suturehas at least two sets of barbs that are offset with respect to eachother, where the first set is aligned longitudinally on the suture andthe second set is aligned longitudinally on the suture, but a planeperpendicular to the suture and cutting transversely through the sutureand intersecting the base of a barb of the first set will not intersectthe base of a barb of the second set.

The barbs project from the exterior surface of the suture body on whichthe barbs are disposed. Depending on the intended end use of the barbedsuture, barbs of different sizes may be employed. In general, largerbarbs are more suitable for joining certain types of tissue such as fattissue or soft tissue. On the other hand, smaller barbs are moresuitable for joining other types of tissue, such as collagen densetissue.

As noted above, barbed sutures may be made from the same materials usedfor making conventional loop sutures. Any particular chosen material forthe barbed suture depends on the strength and flexibility requirements.

More specifically, barbed sutures may be formed from a bio-absorbablematerial that allows the suture to degrade and thus to be absorbed overtime into the tissue as the wound heals. Generally, bio-absorbablematerials are polymeric, and depending on the particular polymerselected, the degradation time in the wound ranges from about 1 month toover 24 months. The use of bio-absorbable materials eliminates thenecessity of removing the sutures from the patient.

Various bio-absorbable polymers include, but are not limited to,polydioxanone, polylactide, polyglycolide, polycaprolactone, andcopolymers thereof. Commercially available examples are polydioxanone(sold as PDS II, a trade name used by Ethicon for selling surgicalsutures), copolymer of about 67% glycolide and about 33% trimethylenecarbonate (sold as MAXON®, a trademark registered to American Cyanamidfor surgical sutures), and copolymer of about 75% glycolide and about25% caprolactone (sold as MONOCRYL®, a trademark registered to Johnson &Johnson for sutures and suture needles). Barbed sutures made from suchbio-absorbable materials are useful in a wide range of applications.

Additionally, barbed sutures may be formed from a non-absorbablematerial, which may be a polymer. Such polymers include, but are notlimited to, polypropylene, polyamide (also known as nylon), polyester(such as polyethylene terephthlate, abbreviated here as PET),polytetrafluoroethylene (such as expanded polytetrafluoroethylene,abbreviated here as ePTFE and sold by Gore as GORTEX®) polyether-ester(such as polybutester, which is the condensation polymerization ofdimethyl terephthlate, polytetramethylene ether glycol, and1,4-butanediol, and which is marketed by Davis & Geck and by U.S.Surgical, companies owned by Tyco, under the name NOVAFIL®, which is atrademark registered to American Cyanamid for surgical sutures), orpolyurethane. Alternatively, the non-absorbable material may be metal(e.g., steel), metal alloys, natural fiber (e.g., silk, cotton, etcetera), and the like.

Most of the barbed sutures discussed below are described as having theirends being pointed and formed of a material sufficiently stiff to allowfor piercing tissue. It is contemplated that the ends of the barbedsutures may comprise a surgical needle. In this embodiment, the barbedsuture is adapted for attachment, such as by swaging, channel wrapping,heat shrinking, or eyelet threading to the surgical needle for insertioninto tissue.

Attachment by swaging is well described and is typically accomplished byinserting the suture end into the surgical needle hole that islongitudinally disposed at one end of the surgical needle (usually thehole has been drilled longitudinally into one end of the needle),followed by crimping the resultant about the needle hole so that thesuture is secured to the surgical needle for insertion into tissue.Also, some surgical needles with a longitudinal hole in one end areheat-shrinkable tubes that are heat shrunk after insertion of the suturein order to attach the suture to the surgical needle. Additionally, somesurgical needles have a channel or trough at one end, and the suture islaid in the trough, followed by wrapping to secure the suture to thesurgical needle. Surgical needles with a conventional eyelet type ofhole transversely disposed in one end of the surgical needle could alsobe used, but are not preferred for barbed sutures. For the presentinvention, part of the discussion below regards surgical needles swagedwith barbed sutures, but it is contemplated that any other suitablemeans of attaching needles can be employed.

Attachment of sutures and surgical needles is described in U.S. Pat. No.3,981,307 Borysko, U.S. Pat. No. 5,084,063 to Korthoff, U.S. Pat. No.5,102,418 to Granger et al., U.S. Pat. No. 5,123,911 to Granger et al.,U.S. Pat. No. 5,500,991 to Demarest et al., U.S. Pat. No. 5,722,991 toColligan, U.S. Pat. No. 6,012,216 to Esteves et al., and U.S. Pat. No.6,163,948 to Esteves et al. A method for the manufacture of surgicalneedles is described in U.S. Pat. No. 5,533,982 to Rizk et al. Further,it is noted that the surgical needle may be coated, the coating allowingfor the needle of the inventive combination surgical needle/barbedsuture to be inserted into tissue with less force than if the surgicalneedle were not coated. The coating may be a polymer, for instance, asilicone resin coating. For example, an improved siliconized surgicalneedle that requires significantly less force to effect tissuepenetration than a standard siliconized surgical needle is described inU.S. Pat. No. 5,258,013 to Granger et al.

The barbs are disposed in various arrangements on the body of thesuture. The barbs may be formed using any suitable method, includinginjection molding, stamping, cutting, laser, and the like. With regardto cutting, in general, polymeric threads or filaments are purchased,and then the barbs are cut onto the filament body.

The cutting may be manual, but that is labor intensive and not costeffective.

A very suitable cutting machine is disclosed in U.S. patent applicationSer. No. 09/943,733 to Genova et al., assignors to Quill Medical, filedAug. 31, 2001, the disclosure of which is incorporated by reference.Such a cutting machine has a plurality of blades for escarpment of barbsonto a suture filament. A typical cutting machine for manufacturingbarbed sutures utilizes a cutting bed, a vise, one or more bladeassemblies, and sometimes a template or guide for the blades. The suturefilament is placed in the bed and held by the vise, with the transversedirection of the blades generally disposed in the transverse directionof the suture filament, in order to cut a plurality of axially spacedbarbs disposed on the exterior of a suture filament.

With reference now to the drawings, where like reference numeralsdesignate corresponding or similar elements throughout the severalviews, shown in FIG. 1A is a side view of a barbed suture according tothe present invention and generally designated at 1.

Suture 1 includes elongated body 2 that is generally circular in crosssection and that terminates in end 4. End 4 is illustrated in oneembodiment as being pointed for penetrating tissue, but it iscontemplated that end 4 may comprise a surgical needle (not shown) forinsertion into tissue. (The other end is not shown.) Also, suture 1includes plurality of closely spaced barbs 7, 9 arranged in a staggereduni-directional disposition. More specifically, axially spaced barbs 7are radially arranged about 180 degrees from and staggered with respectto axially spaced barbs 9, with barbs 7, 9 facing pointed end 4. Firstset of barbs 7 define a plane that is substantially coplanar with theplane defined by second set of barbs 9, and consequently, barbs 7, 9define substantially the same one plane due to the radial 180 degreearrangement.

FIG. 1B, which is a cross sectional view along line 1B-1B of suture 1 inFIG. 1A, more clearly illustrates angle X, namely the radial 180 degreearrangement of barbs 7 with respect to barbs 9. As also can be seen fromFIG. 1B, the stippling illustrates that first barb 7 of barbs 7 iscloser to pointed end 4 (not shown in FIG. 1B), and thus, seems to belarger than farther away first barb 9 of barbs 9, due to the staggering.A transverse plane that is perpendicular to suture body 2 and thatintersects the base of one barb 7 of barbs 7 does not intersect the baseof any barb 9 of barbs 9.

Suture 1 may be made with a cutting machine that produces two sets ofbarbs 7, 9, usually one set at a time, in a staggered position alongsuture 1, such as the cutting device described in the above-noted Ser.No. 09/943,733 to Genova et al.

First set of barbs 7 is created by placing and holding a suture filamentin the vise, and then, the set of blades, with a predetermined length,splices into the suture filament at an angle selected to create barbs 7pointing in one direction toward pointed end 4. Second set of barbs 9 iscreated similarly after offsetting the blades longitudinally (to createthe staggering) approximately half of the longitudinal distance betweentwo of barbs 7 and also rotating the suture filament about 180 degreeson the vise, which is equipped to accommodate first set of barbs 7 thatare already cut.

Shown in FIG. 2A is suture 10, which is another embodiment of thepresent invention and is like suture 1, except that suture 10 isbidirectional. Suture 10 includes elongated body 12 that is generallycircular in cross section. Elongated body 12 terminates in first andsecond pointed ends 14, 16 for penetrating tissue. Also, it iscontemplated that one or both ends 14, 16 may comprise a surgical needle(not shown) for insertion into tissue. Also, suture 10 includesplurality of closely spaced barbs 17, 18, 19, 20 arranged in a staggeredbidirectional disposition.

More specifically, plurality of axially spaced barbs 17 are radiallyarranged about 180 degrees from and staggered with respect to pluralityof axially spaced barbs 19, with barbs 17, 19 facing pointed end 14 fora portion (about half of the length) of suture 10. Similarly, pluralityof axially spaced barbs 18 are radially arranged about 180 degrees fromand staggered with respect to plurality of axially spaced barbs 20, withbarbs 18, 20 facing pointed end 16 for another portion (approximatelythe other half of the length) of suture 10. First set of barbs 17, 18define a plane that is substantially coplanar with the plane defined bysecond set of barbs 19, 20. As a result, all of barbs 17, 18, 19, 20define substantially the same one plane due to the radial 180 degreearrangement of first set of barbs 17, 18 with respect to second set ofbarbs 19, 20.

FIG. 2B is a cross sectional view along line 2B-2B of suture 10 in FIG.2A, more clearly illustrating angle X, namely the radial 180 degreearrangement. Due to the staggering, first barb 17 of barbs 17 is closerto pointed end 14 (not shown in FIG. 2B), and thus, appears larger thanfarther away first barb 19 of barbs 19, as is illustrated by thestippling. A transverse plane that is perpendicular to suture body 12and that intersects the base of one barb 17 of barbs 17 does notintersect the base of any barb 19 of barbs 19. Likewise, a transverseplane that is perpendicular to suture body 12 and that intersects thebase of one barb 18 of barbs 18 does not intersect the base of any barb20 of barbs 20.

Suture 10 may be made with the same cutting machine as suture 1, such asthe cutting device described in the above-noted Ser. No. 09/943,733 toGenova et al., except with the following change in blade direction.

For first set of bidirectional barbs 17, 18, after the suture filamentis placed and held in the vise, the blades splice with a first cuttingaction into approximately half of the length of the suture filament tocreate barbs 17 facing in one direction toward pointed end 14. Next, theblades are rotated 180 degrees so that they are now disposed in theopposite direction and over the uncut half of the length. The blades arethen allowed to splice into the other half of the length of the suturefilament with a second cutting action to create barbs 18 facing in theopposite direction toward pointed end 16.

Next, the blades are offset longitudinally (to create the staggering)about half of the longitudinal distance between two of barbs 17, andalso the suture filament is rotated about 180 degrees on the vice, whichis equipped to accommodate first set of bidirectional barbs 17, 18 thatare already cut. Then, for second set of bidirectional barbs 19, 20, theblades splice with a first cutting action into approximately half thelength of the suture filament to create barbs 20 facing in one directiontoward pointed end 16. The first cutting action is followed by rotatingthe blades longitudinally 180 degrees so that they are now disposed inthe opposite direction and over the uncut half of the length. The bladesare then allowed to splice into the other half of the length of thesuture filament with a second cutting action to create barbs 19 facingin the opposite direction toward pointed end 14.

In an alternative embodiment (not shown) for bidirectional suture 10,the portion of suture 10 with barbs 17, 19 may have them facing towardpointed end 16 and the portion of suture 10 with barbs 18, 20 may havethem facing toward pointed end 14. With this variation, the barbedsuture would be inserted into tissue with an insertion device, such asthat shown in the above-noted U.S. Pat. No. 5,342,376 to Ruff.Additionally, it is noted that, if desired, barbs may be escarped sothat there may be two portions with barbs facing one end and one portionwith barbs facing the other end, or two portions with barbs facing oneend and two portions with barbs facing the other end, and so on (notshown), and thus, if a portion of barbs is not facing the suture end towhich those barbs are adjacent, then, the barbed suture would beinserted into tissue with an insertion device.

An advantage of a barbed suture having a radial 180 degree arrangementwith staggering is that the 180 degree spacing is readily fabricated onrelatively small diameter filaments and the staggering improvesanchoring performance. Thus, in thin and delicate tissue, where asmaller suture is desirable, the staggered 180 degree spacing generateseffective anchoring performance.

Turning now to FIG. 3A, depicted is a side view of another embodiment ofa suture according to the present invention, and generally designated atsuture 30. Suture 30 is like suture 1 shown in FIG. 1A, except that theradial spacing for suture 30 is 120 degrees instead of 180 degrees as isshown for suture 1.

More particularly, suture 30 includes elongated body 32 that isgenerally circular in cross section and that terminates in pointed end34 for penetrating tissue. It is contemplated that end 34 may comprise asurgical needle (not shown) so that the suture can be inserted intotissue. (The other end is not shown.) Additionally, suture 30 includesplurality of closely spaced barbs 35, 37, 39 arranged so that all facein the same direction toward pointed end 34. Hence, the disposition ofbarbs 35, 37, 39 is unidirectional.

Also, axial spaced barbs 35 are radially arranged about 120 degrees fromand staggered with respect to axially spaced barbs 37, which areradially arranged about 120 degrees from and staggered with respect toaxially spaced barbs 39. Hence, axially spaced barbs 39 are alsoarranged about 120 degrees from and staggered with respect to axiallyspaced barbs 35. As a result of the radial 120 degree arrangement, firstset of barbs 35 define substantially the same one plane; second set ofbarbs 37 define substantially another same one plane; and third set ofbarbs 39 define substantially still another same one plane. Thus, suture30 has barbs 35, 37, 39 arranged in a staggered uni-directional 120degree disposition.

FIG. 3B is a cross sectional view along line 3B-3B of suture 30 in FIG.3A and shows with more particularity angle Y, namely the radial 120degree arrangement of barbs 35 with respect to barbs 37, barbs 37 withrespect to barbs 39, and barbs 39 with respect to barbs 35.

As illustrated by the stippling, first barb 35 of barbs 35, because ofthe staggering, is closer to pointed end 34 (not shown in FIG. 3B), andthus, seems to be larger than farther away first barb 37 of barbs 37.Also, first barb 37 of barbs 37, due to the staggering, is closer topointed end 34 (not shown in FIG. 3B), and thus, seems to be larger thaneven farther away first barb 39 of barbs 39. A transverse plane that isperpendicular to suture body 32 and that intersects the base of one barb35 of barbs 35 does not intersect the base of any barb 37 of barbs 37.Likewise, a transverse plane that is perpendicular to suture body 32 andthat intersects the base of one barb 37 of barbs 37 does not intersectthe base of any barb 39 of barbs 39. Similarly, a transverse plane thatis perpendicular to suture body 32 and that intersects the base of onebarb 39 of barbs 39 does not intersect the base of any barb 35 of barbs35.

Suture 30 may be made with the same cutting machine as suture 1, such asthe cutting device described in the above-noted Ser. No. 09/943,733 toGenova et al. The cutting machine is now used to produce three sets ofbarbs 35, 37, 39, usually one set at a time, in a staggered positionalong suture 30.

First set of barbs 35 is created by placing and holding a suturefilament in the vise, followed by the blades, after having been adjustedto a predetermined length, splicing into the suture filament at an anglethat is chosen to create barbs 35 so that all are facing in the samedirection toward pointed end 34.

Next, the blades are offset longitudinally (to create the staggering)approximately half of the longitudinal distance between two of barbs 35.Also, the filament is rotated about 120 degrees on the vise, which isequipped to accommodate first set of barbs 35 that have already beencut, and then second set of barbs 37 is created in a similar manner.

Likewise, the blades are again offset longitudinally (to create thestaggering) approximately half the longitudinal distance between two ofbarbs 35, and also the suture filament is rotated about 120 degrees onthe vise, which is equipped to accommodate both already cut first set ofbarbs 35 and already cut second set of barbs 37. Following thelongitudinal movement and rotation, third set of barbs 39 is created ina similar manner.

Preferably, each successive barb is escarped at a position about 120degrees, around suture body 32 from the preceding barb and does notoverlap with any other barb.

With reference now to FIG. 4A, illustrated is suture 40, anotherembodiment of the present invention. Suture 40 is similar to suture 30,except that suture 40 is bi-directional. Suture 40 includes elongatedbody 42 that is generally circular in cross section and that terminatesin first and second pointed ends 44, 46 for penetrating tissue. Also, itis contemplated that one or both ends 44, 46 may comprise a surgicalneedle (not shown) in order to be inserted into tissue. Suture 40further includes plurality of closely spaced barbs 47, 48, 49, 50, 51,52 arranged in a staggered bi-directional disposition.

For about half of the length of suture 40, axially spaced barbs 47 arecircumferentially arranged about 120 degrees from and staggered withrespect to axially spaced barbs 49, which are radially arranged about120 degrees from and staggered with respect to axially spaced barbs 51.Consequently, axially spaced barbs 51 are also arranged about 120degrees from and staggered with respect to axially spaced barbs 47.Thus, a portion of suture 40 has all of barbs 47, 49, 51 facing in thesame direction toward pointed end 44.

For the other half of the length of suture 40, axially spaced barbs 48are radially arranged about 120 degrees from and staggered with respectto axially spaced barbs 50, which are radially arranged about 120degrees from and staggered with respect to axially spaced barbs 52.Consequently, axially spaced barbs 52 are also arranged about 120degrees from and staggered with respect to axially spaced barbs 48.Thus, another portion of suture 40 has all of barbs 48, 50, 52 facing inthe same direction toward pointed end 46.

As a result of the radial 120 degree arrangement, first set of barbs 47,48 define substantially the same one plane; second set of barbs 49, 50define substantially another same one plane; and third set of barbs 51,52 define substantially still another same one plane.

FIG. 4B, which is a cross sectional view along line 4B-4B of suture 40in FIG. 4A, shows more clearly angle Y, namely the radial 120arrangement with greater specificity. As illustrated by the stippling,first barb 47 of barbs 47, on account of the staggering, is closer topointed end 44 (not shown in FIG. 4B), and thus, appears larger thanfarther away first barb 49 of barbs 49. Also because of the staggering,first barb 49 of barbs 49 is closer to pointed end 44 (not shown in FIG.4B), and thus, appears larger than even farther away first barb 51 ofbarbs 51.

A transverse plane that is perpendicular to suture body 42 and thatintersects the base of one barb 47 of barbs 47 does not intersect thebase of any barb 49 of barbs 49. Likewise, a transverse plane that isperpendicular to suture body 32 and that intersects the base of one barb49 of barbs 49 does not intersect the base of any barb 51 of barbs 51.Similarly, a transverse plane that is perpendicular to suture body 42and that intersects the base of one barb 51 of barbs 51 does notintersect the base of any barb 47 of barbs 47. Also, a transverse planethat is perpendicular to suture body 42 and that intersects the base ofone barb 48 of barbs 48 does not intersect the base of any barb 50 ofbarbs 50. Likewise, a transverse plane that is perpendicular to suturebody 32 and that intersects the base of one barb 50 of barbs 50 does notintersect the base of any barb 52 of barbs 52. Similarly, a transverseplane that is perpendicular to suture body 42 and that intersects thebase of one barb 52 of barbs 52 does not intersect the base of any barb48 of barbs 48.

Suture 40 may be made with the same cutting machine as suture 1, such asthe cutting device described in the above-noted Ser. No. 09/943,733 toGenova et al., except with the following change in blade direction.

For first set of bi-directional barbs 47, 48, after the suture filamentis placed and held in the vise, the blades splice with a first cuttingaction into approximately half of the length of the suture filament tocreate barbs 47 facing in one direction toward pointed end 44. Then, theblades are rotated 180 degrees so that they are now disposed in theopposite direction and over the uncut half of the length. The bladesthen are allowed to splice into the other half of the length of thesuture filament with a second cutting action to create barbs 48 facingin the opposite direction toward pointed end 46.

Next, the blades are offset longitudinally (to create the staggering)for about half the longitudinal distance between two of barbs 47, andalso the suture filament is rotated about 120 degrees on the vise, whichis equipped to accommodate first set of bi-directional barbs 47, 48 thatare already cut. Then, for second set of bi-directional barbs 49, 50,the blades splice with a first cutting action into approximately half ofthe length of the suture filament to create barbs 50 facing in onedirection toward pointed end 46. The first cutting action is followed byrotating the blades 180 degrees so that they are now disposed in theopposite direction and over the uncut half of the suture filament. Theythen splice into the other half of the length of the suture filamentwith a second cutting action to create barbs 49 facing in the oppositedirection toward pointed end 44.

Then, the blades are again offset longitudinally (to create thestaggering) for about half the longitudinal distance between two ofbarbs 47. Additionally, the suture filament again is rotated about 120degrees on the vise, which is equipped to accommodate already cut firstset of bidirectional barbs 47, 48 and already cut second set ofbidirectional barbs 49, 50. Following the longitudinal movement androtation, the third set of bidirectional barbs 51, 52 are made by havingthe blades splice with a first cutting action into approximately half ofthe length of the suture filament to create barbs 51 facing in onedirection toward pointed end 44. The first cutting action is followed byrotating the blades 180 degrees so that they are now disposed in theopposite direction and over the uncut half of the suture filament. Theynext splice into the other half of the length of the suture filamentwith a second cutting action to create barbs 52 facing in the oppositedirection toward pointed end 46.

Preferably, each successive barb is escarped at a position about 120degrees around suture body 42 from the preceding barb and does notoverlap with any other barb.

In an alternative embodiment (not shown) for bidirectional suture 40,the portion of suture 40 having barbs 47, 49, 51 may have them facingtoward pointed end 46 and the portion of suture 40 having barbs 48, 50,52 may have them facing toward pointed end 44. With this variation, thebarbed suture would be inserted into tissue with an insertion device,such as that shown in the above-noted U.S. Pat. No. 5,342,376 to Ruff.Additionally, it is noted that, if desired, barbs may be escarped sothat there may be two portions with barbs facing one end and one portionwith barbs facing the other end, or two portions with barbs facing oneend and two portions with barbs facing the other end, and so on (notshown), and thus, if a portion of barbs is not facing the suture endthat those barbs are adjacent, then, the barbed suture would be insertedinto tissue with an insertion device.

An advantage of a barbed suture with a radial 120 degree arrangement isthat the barbs exert force in three distinct planes that compliment eachother, resulting in maximization of the retention force of the sutureoverall. As noted above, the staggering enhances anchoring performance.

Turning now to FIG. 5A, shown is another embodiment of the presentinvention, which is generally designated at suture 60, with radialspacing that is in a twist cut multiple spiral. Suture 60 includeselongated body 62 of generally circular cross section. Elongated body 62terminates in pointed end 64 for penetrating tissue. Also, it iscontemplated that end 64 may comprise a surgical needle (not shown) forinsertion into tissue. Furthermore, suture 60 includes plurality ofclosely spaced barbs 67 arranged in a twist cut multiple spiral patternaround body 62 and facing in the same direction toward pointed end 64.

FIG. 5B is a cross sectional view along line 5B-5B of suture 60 in FIG.5A. Due to the twist cut multiple spiral disposition, each respectivebarb 67 seems to be smaller and smaller as each is farther and fartheraway from pointed end 64 (not shown in FIG. 5B), the illusion of sizedifference being illustrated by the stippling.

Suture 60 may be constructed with a similar cutting machine as that usedfor making suture 1, such as the cutting device described in theabove-noted Ser. No. 09/943,733 to Genova et al. With a twist cuttingmethod, barbs 67 may be produced in multiple spirals that preferably arecreated at the same time as the suture filament is held stationary,instead of being rotated, when the cutting takes place.

More particularly, a suture filament that is about 7 inches (about 178mm) in length, is longitudinally twisted for a portion of the suturelength, such as 39 times for a portion that is about 4.5 inches (about114 mm) of the suture length. Thus, an end is secured, and the other endis grasped and rotated 360 degrees, 39 times, so the portion of thesuture filament is twisted when the suture is then placed and held inthe vise.

Twisting preferably is performed 28 to 50 times, and may be performedmore or less, such as 19 to 70 times. Suitably, twisting may be fromabout 2 to about 17 twists per inch, or about 3 to about 15 twists perinch, or about 5 to about 13 twists per inch (per inch being per 25.4mm)

Next, the blades, after having been adjusted to a predetermined length,simultaneously splice into the suture filament. The cutting action makescuts to create barbs 67 so that all are facing in the same directiontoward pointed end 64. After twist cut multiple spiral barbed suture 60is released from the vice and untwisted, barbs 67 are disposed inmultiple spirals on suture 60.

Turning now to FIG. 6A, shown is another embodiment of the presentinvention, which is generally designated at suture 70. Suture 70 is of atwist cut multiple spiral disposition and thus is similar to suture 60,except that suture 70 is bidirectional. Suture 70 includes elongatedbody 72 that is generally circular in cross section and that terminatesin first and second pointed ends 74, 76 for penetrating tissue. It iscontemplated that one or both of ends 74, 76 may comprise a surgicalneedle (not shown) for insertion into tissue.

Suture 70 further includes plurality of closely spaced barbs 77, 78arranged in two respective spiral patterns, each being a multiple spiralaround body 72. Barbs 77, 78 are disposed on middle portion MP that isapproximately 3 inches (approximately 76 mm) of suture 70, with each endportion EP of suture 70 being barb-free. More particularly, plurality ofbarbs 77 are arranged in a multiple spiral pattern with all barbs 77facing toward pointed end 74 for a part (about half) of middle portionMP along the length of suture 70. Similarly, plurality of barbs 78 arearranged in a multiple spiral pattern with all barbs 78 facing towardpointed end 76 for another part (the other approximate half) of middlepotion MP along the length of suture 70.

FIG. 6B is a cross sectional view along line 6B-6B of suture 60 in FIG.6A. Due to the multiple spiral configuration, each respective barb 77seems to be smaller and smaller as each is farther and farther away frompointed end 74 (not shown in FIG. 6B), as illustrated by the stippling.

Suture 70 may be made with the same cutting machine as suture 60, suchas the cutting device described in the above-noted Ser. No. 09/943,733to Genova et al., but with the following change in blade direction.Using the twist cutting method, barbs 77 may be produced in multiplespirals that preferably are created at the same time, and then after thedirection change for the blades, barbs 78 may be produced in multiplespirals that preferably are created at the same time. Thus during thecutting, the suture filament is held stationary instead of beingrotated.

More specifically, a section of about 4.5 inches (about 114 mm) inlength of a suture filament is twisted, such as 39 times for a sutureabout 7 inches (about 178 mm) in length. Thus, an end is secured, andthe other end is grasped and rotated 360 degrees, 39 times, so thetwisted section of the suture filament has about 8⅔ twists per inch (per25.4 mm) when the suture filament is then is placed and held in thevise.

Twisting preferably is performed 28 to 50 times, and may be performedmore or less, such as 19 to 70 times. Suitably, twisting may be fromabout 2 to about 17 twists per inch, or about 3 to about 15 twists perinch, or about 5 to about 13 twists per inch (per inch being per 25.4mm).

Next, the blades, after having been adjusted to a predetermined length,splice into approximately half of the approximately 3 inch(approximately 76 mm) length of middle portion MP of the approximately4.5 inch (approximately 114 mm) twisted section of the suture filamentin a first cutting action with the blades making cuts to create barbs 77so that all are facing in one direction toward pointed end 74. Dependingon how many blades there are on the cutting machine and how many barbs77 are desired, there may be one cutting motion to cut all barbs 77simultaneously, or there may be repeated cutting motions until thedesired number of barbs 77 are escarped into a portion of the suturefilament.

Then, the blades are rotated 180 degrees so that they are now disposedin the opposite direction and over the other half of the approximately 3inch (approximately 76 mm) length of middle portion MP of theapproximately 4.5 inch (approximately 114 mm) twisted section of thesuture filament. The blades are then allowed to splice into the otherhalf in a second cutting action with the blades making cuts to createbarbs 78 so that all are facing in the opposite direction toward pointedend 76. Depending on how many blades there are on the cutting machineand how many barbs 78 are desired, there may be one cutting motion tocut all barbs 78 simultaneously, or there may be repeated cuttingmotions until the desired number of barbs 78 are escarped into a portionof the suture filament.

When twist cut multiple spiral barbed suture 70 is released from thevise and untwisted, the first cuts and the second cuts result in barbs77, 78 being in two respective multiple spiral patterns on tworespective portions of suture 70, the two respective portions definingmiddle portion MP of about 3 inches (about 76 mm) in length.

More particularly, several twist cut multiple spiral, barbed sutureswere manufactured from a monofilament having a diameter of about 0.018inch (about 0.457 mm) and spun from polydioxanone (which is a syntheticabsorbable suture material). A diameter of about 0.018 inch (about 0.457mm) is slightly larger than the size 0 synthetic absorbable suture,which has a diameter range from about 0.35 mm to about 0.399 mm inaccordance with the specifications of the United States Pharmacopoeia(USP).

Each suture contained a total of 78 barbs introduced in two respectivemultiple spiral patterns around the circumference of the suture. Sincethe barbed suture was bi-directional, the barbs were divided into a leftgroup with 39 barbs disposed on a first portion of the suture and aright group with 39 barbs on a second portion of the suture, each groupopposing the direction of the other group from the approximate middle ofthe suture. The specific cutting machine employed had 13 blades. Thus,for each group of 39 barbs, there were 3 cutting motions (3×13=39), withthe blades being offset with a guide for each of the 3 cutting motions.

Each suture was about 7 inches (about 178 mm) long. The middle portionMP was about 3 inches (about 76 mm) long and contained the 78 barbs thatwere escarped into the suture filament. Extending beyond the 3 inch (76mm) barbed middle portion MP were two unbarbed end portions EP of thesuture that were each about 2 inches (about 51 mm) long. Depending onthe suturing technique, one or both ends of the barbed suture may besufficiently pointed and rigid for insertion into tissue, or maycomprise a straight or curved surgical needle.

The strength of the twist cut, 7 inch (178 mm) barbed sutures was testedby two methods. One method was a straight pull tensile strength testwith a Universal Tester and the other method was an in vivo performancetest with dogs.

For the straight pull tensile strength measurement, testing wasperformed using a Test Resources Universal Tester, Model 200Q. Theaverage reading of 10 repeated measurements made for each kind of suturewas recorded for the barbed sutures and for the comparison unbarbedsutures.

Comparison unbarbed sutures were polydioxanone monofilaments (asynthetic absorbable suture material) of various suture diameters ofabout 0.018 inch (about 0.457 mm), about 0.015 inch (about 0.381 mm),and about 0.0115 inch (about 0.292 mm), which are respectively slightlylarger than the United States Pharmacopoeia sizes 0, 2-0, and 3-0 forsynthetic absorbable sutures. In accordance with United StatesPharmacopoeia specifications for synthetic absorbable sutures, size 0has a diameter range of about 0.35 mm to about 0.399 mm; size 2-0 has adiameter range of about 0.30 mm to about 0.339 mm; and size 3-0 has adiameter range of about 0.20 mm to about 0.249 mm.

Each barbed suture was gripped at each end by being held with corkgasket padding in two respective serrated jaws, whereas each unbarbedsuture was gripped at each end by being wrapped around two respectivecapstan roller grips. Capstan rollers were used for holding the unbarbedsutures to avoid stress and distension.

The portion of each suture specimen between the two gripped places wasabout 5 inches (about 126 mm) in length, which, in the case of barbedsutures, contained the entire 3 inches (76 mm) of the barbed middleportion.

Each specimen was pulled longitudinally at a rate of about 10 inches(about 254 mm) per minute until breakage occurred. The peak load wasrecorded as the straight pull tensile strength.

The results are summarized in Table 6A below, and the far right columndenotes the USP knot pull test minimum requirements for conventional(unbarbed) sutures made from a synthetic absorbable material.

TABLE 6A (Tensile Strength) Barbed or Suture Straight Pull USP MinimumRequirements Unbarbed Size (pounds) for Knot Pull (pounds) Unbarbed 017.72 8.60 Unbarbed 2-0 11.86 5.91 Unbarbed 3-0 8.82 3.90 Barbed 0 7.03not applicable

As can be seen, escarpment of barbs into the size 0 polydioxanonemonofilament reduced the straight pull tensile strength by approximately60% as compared to the conventional unbarbed size 0 polydioxanonemonofilament (7.03 pounds=40% of 17.72 pounds).

However, the straight pull tensile strength of 7.03 pounds at breakagefor the size 0 polydioxanone barbed suture (which, due to the escarpmentof the barbs, has an effective diameter that is smaller than thediameter of the conventional unbarbed size 0 polydioxanone suture)compared favorably with the minimum USP knot pull requirement of 8.60pounds for the size 0 polydioxanone conventional unbarbed suture.

6] Additional straight pull tensile strength tests were performed onadditional size 0 polydioxanone barbed sutures, as discussed below inTables 7K-7Z, in connection with FIGS. 7A and 7B.

For the in vivo performance, 3 mongrel dogs, each about 14 kg, wereused. On each dog, 7 incisions were made at the thorax (twice), thigh(twice), flank, ventral midline, and paramedian, each of the 7 incisionshaving 1, 2, or 3 closure sites. The length of each incision ranged fromabout 0.5 inch (about 12.5 mm) to about 4 inches (about 101 mm) and thedepth of each incision was from the superficial dermis to theperitoneum.

Using the barbed sutures (all made from size 0 polydioxanonemonofilament), 24 of the sites were closed. For comparison, theremaining sites were closed with various diameter sizes of conventionalunbarbed sutures (1 site with size 2-0 silk braided filament, 6 siteswith size 2-0 nylon monofilament, and 7 sites with size 3-0polydioxanone monofilament), which were knotted. All closing of siteswas performed according to a randomized scheme.

The dogs were monitored daily, and then subjected to euthanasia at 14days. At the time of death, the incisions were evaluatedmacroscopically. With regard to various tissues, incision sizes, andlocations on the dogs, all sites apposed with the size 0 polydioxanonebarbed sutures stayed closed and appeared to be healing normallythroughout the 14 day observation period. No dehiscence occurred.

The site apposed with the conventional unbarbed silk sutures and thesites apposed with the conventional unbarbed polydioxanone sutures alsohealed will without complications. No dehiscence occurred.

For the 6 topical skin sites closed with the size 2-0 nylon monofilamentconventional unbarbed sutures, 3 sites exhibited partial or completesuture loss, apparently due to self-mutilation by the dogs. Knots in theconventional sutures possibly caused discomfort by creating localizedpressure, and animals cannot understand that they should not manipulatethe sutures. Thus, barbed sutures should help obviate the problem of ananimal manipulating and pulling out the sutures.

In summary, the in vivo performance of the size 0 polydioxanone barbedsutures was efficacious when compared to the size 2-0 silk braidedfilament unbarbed sutures, the size 2-0 nylon monofilament unbarbedsutures, and the size 3-0 polydioxanone monofilament unbarbed sutures.

In an alternative embodiment (not shown) for bidirectional twist cut,multiple spiral suture 70, the portion of suture 70 on which is disposedbarbs 77 may have barbs 77 facing toward pointed end 76 and the portionof suture 70 on which is disposed barbs 78 may have barbs 78 facingtoward pointed end 74. With this variation, the barbed suture would beinserted into tissue with an insertion device, such as that shown in theabove-noted U.S. Pat. No. 5,342,376 to Ruff. Also if desired, it isnoted that barbs may be escarped so that there may be 2 portions withbarbs facing an end and 1 portion with barbs facing the other end, or 2portions with barbs facing an end and 2 portions with barbs facing theother end, and so on (not shown), and thus, if a portion of barbs is notfacing the suture end to which those barbs are adjacent, then, thebarbed suture would be inserted into tissue with an insertion device.

An advantage of a barbed suture having a twist cut, multiple spiraldisposition is that such a barbed suture affords better wound holdingcapability as compared to the 120 degree spaced barbed suture. Thereason is that the twist cut, multiple spiral pattern results in groupsof barbs that complement successive and preceding groups of barbs, whichtends to provide improved anchoring when the suture is in tissue. Thisfeature is especially useful for tissue such as fat tissue, which hasfewer connective fibers compared with other types of tissues, so thatgreater suture retention force is desirable.

With reference now to FIG. 7A, shown is a sectional side view of barbedsuture 80. Barbed suture 80 has plurality of closely spaced barbs 81 onelongated suture body 82 of generally circular cross section. Each barb81 has barb tip 85. Shown are suture longitudinal axis A, suturediameter SD, barb length L, barb cut depth D, barb cut angle θ, cutdistance P, spirality angle α, cut-out depression CD, and tip T ofcut-out depression CD.

FIG. 7B is the sectional side view as illustrated in FIG. 7A, butrotated and clamped to align the barbs for measurement of the cutdistance P between barbs 81.

Barbed suture 80 is a twist cut, multiple spiral, bidirectional barbedsuture, like suture 70 in FIG. 6A, but illustrated as an enlargedsection in order to show more detail with respect to the configurationof barbs 81 vis-à-vis suture longitudinal axis A, suture diameter SD,barb length L, barb cut depth D, barb cut angle θ, cut distance P,spirality angle α, cut-out depression CD, and terminus T of cut-outdepression CD.

More specifically, several twist cut, multiple spiral, barbed sutureswere manufactured from monofilament spun from polydioxanone and having adiameter of about 0.018 inch (about 0.457 mm, which is slightly morethan the USP requirement for a size 0 synthetic absorbable suture). Eachsuture contained 78 barbs introduced in 2 separate multiple spiralpatterns around the circumference of the suture. Since the barbs werebi-directional, they were divided into a left group with 39 barbs and aright group with 39 barbs, each group opposing the direction of theother group from the approximate middle of the suture. Each suture wasabout 7 inches (about 178 mm) long. The middle portion was about 3inches (about 76 mm) of the suture and contained the 78 barbs that wereescarped into the suture filament. Extending beyond the 3 inch (76 mm)barbed middle portion toward each suture end were two unbarbed endportions of the suture filament that were each about 2 inches (about 51mm) long. Depending on the stitching technique, one or both ends of thebarbed suture may be sufficiently pointed and rigid for insertion intotissue, or may comprise a straight or curved needle.

In order to characterize the configuration of barbs 81, an Optem Zoom100 custom microscope with both ring and back lighting was used togetherwith a CCD brand video camera in order to measure selected barbs 81 at×21.5 magnification from each of the left and right groups.

The average was calculated for 10 repeated measurements (5 from the leftgroup of barbs and 5 from the right group of barbs on the same suture)that were made for each of cut angle θ and cut depth D. Barb cut angle θwas measured from the surface of the cut to the outer surface of barbedsuture 80. Barb cut depth D was measured along a perpendicular from theouter surface of barbed suture 80 toward longitudinal axis A of barbedsuture 80. The measurements enabled cut length L to be calculated usingthe following formula.

L=D/{Sin (180−θ)}

Also, angle α of spirality was measured microscopically on variousbarbed sutures 80 as follows. When the twisted suture filament isgripped by the vise during cutting of barbs 81, the vise leaves a verylight mark designated as line M impressed on the suture filament. Thus,line M will be parallel to the longitudinal axis of the vise while thetwisted suture filament is being held in the vise. If the vise does notleave a light mark on the suture filament, then line M can be determinedin that it is parallel to a line connecting the two respective terminusT of the two successive cut-out depressions CD left in suture body 82from the escarpment of two successive barbs 81. After cutting of barbs81, when barbed suture 80 is released from the vise and untwisted sothat suture 80 lies free, then line M spirals on suture body 82 aroundbarbed suture 80, forming angle α of spirality.

Specifically for measuring spirality angle α, the Optem Zoom 100 custommicroscope was set with ring lighting at 60 and back lighting at coarse12 and fine 10. Also, imaging analysis system software was used.Spirality angle α was then measured between the outer surface of thebarbed suture and line M. The average was calculated for 10 repeatedmeasurements (5 from the left group of barbs and 5 from the right groupof barbs on the same suture).

Then, barbed suture 80 was mounted in a twisting device with one end ofsuture 80 clamped in a fixed position. The other end of suture 80 wasrotated to insert twist until barbs 81 were aligned. Next on barbedsuture 80, longitudinal cut distance P between two adjacent barbs 81 wasmeasured microscopically between the two respective terminus T of thetwo successive cut-out depressions CD left in suture body 82 from theescarpment of two successive barbs 81. The average was calculated for 10repeated measurements (5 from the left group of barbs and 5 from theright group of barbs on the same suture).

The results are summarized in the following Tables 7A, 7B, 7C, and 7D.

TABLE 7A (size 0 barbed suture) Ratio of D, L, or P over SutureMeasurement Units Left Right Diameter (0.457 mm) cut angle θ degrees 156+/− 2  157 +/− 1  not applicable cut depth D mm 0.15 +/− 0.02 0.16 +/−0.04 0.35 cut length L mm 0.36 +/− 0.03 0.40 +/− 0.10 0.87 cut distanceP mm 0.90 +/− 0.17 0.88 +/− 0.15 1.92

TABLE 7B (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 151 1.642 not applicable cut depth D mm 0.215 0.027 0.47 cutlength L mm 0.446 0.042 0.97 cut distance P mm 0.962 0.073 2.1 spiralityangle α degrees 20.833 1.602 not applicable

TABLE 7C (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 154 2.870 not applicable cut depth D mm 0.205 0.033 0.45 cutlength L mm 0.469 0.044 1.03 cut distance P mm 0.975 0.103 2.13spirality angle α degrees 19.333 1.506 not applicable

TABLE 7D (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 155 2.390 not applicable cut depth D mm 0.186 0.026 0.41 cutlength L mm 0.437 0.039 0.96 cut distance P mm 0.966 0.071 2.11spirality angle α degrees 18.833 2.137 not applicable

Also, some additional measurements of angle α were performed on a fewadditional bidirectional twist cut, multiple spiral barbed sutures witha diameter of about 0.018 inch (about 0.457 mm, slightly more than theUSP requirement for a size 0 synthetic absorbable suture). The meanaverage was 16.87 and the standard deviation was +0.85.

Additionally, measurements of barb cut angle θ, barb length L, barb cutdepth D, and cut distance P were performed on 3 additionalbi-directional twist cut, multiple spiral barbed sutures like sutures80, but having a diameter of about 0.0115 inch (about 0.292 mm, which isslightly more than the USP requirement for a size 3-0 syntheticabsorbable suture), and measurements of spirality angle α were performedon 2 of these 3 additional barbed sutures. Also, measurements of barbcut angle θ, barb length L, barb cut depth D, cut distance P, andspirality angle .alpha. were performed on 3 additional bi-directionaltwist cut, multiple spiral barbed sutures like sutures 80, but with adiameter of about 0.015 inch (about 0.381 mm, which is slightly morethan the USP requirement for a size 2-0 synthetic absorbable suture).The results are summarized in the following Tables 7E, 7F, 7G, 7H, 7I,and 7J.

TABLE 7E (size 3-0 barbed suture) Ratio of D, L, or Standard P overSuture Measurement Units Average Deviation Diameter (0.292 mm) cut angleθ degrees 166 1.651 not applicable cut depth D mm 0.107 0.007 0.37 cutlength L mm 0.443 0.042 1.52 cut distance P mm 0.956 0.079 3.27spirality angle α degrees not not not applicable tested applicable

TABLE 7F (size 3-0 barbed suture) Ratio of D, L, or Standard P overSuture Measurement Units Average Deviation Diameter (0.292 mm) cut angleθ degrees 164 2.055 not applicable cut depth D mm 0.106 0.006 0.36 cutlength L mm 0.395 0.042 1.35 cut distance P mm 0.959 0.074 3.28spirality angle α degrees 7.329 0.547 not applicable

TABLE 7G (size 3-0 barbed suture) Ratio of D, L, or Standard P overSuture Measurement Units Average Deviation Diameter (0.292 mm) cut angleθ degrees 165 1.031 not applicable cut depth D mm 0.104 0.009 0.36 cutlength L mm 0.390 0.035 1.34 cut distance P mm 0.975 0.103 3.34spirality angle α degrees 7.258 0.636 not applicable

TABLE 7H (size 2-0 barbed suture) Ratio of D, L, or Standard P overSuture Measurement Units Average Deviation Diameter (0.381 mm) cut angleθ degrees 160.2 1.320 not applicable cut depth D mm 0.152 0.019 0.40 cutlength L mm 0.449 0.057 1.18 cut distance P mm 0.944 0.098 2.48spirality angle α degrees 9.40 1.606 not applicable

TABLE 7I (size 2-0 barbed suture) Ratio of D, L, or Standard P overSuture Measurement Units Average Deviation Diameter (0.381 mm) cut angleθ degrees 161.0 1.707 not applicable cut depth D mm 0.158 0.014 0.41 cutlength L mm 0.489 0.054 1.28 cut distance P mm 0.962 0.054 2.52spirality angle α degrees 7.96 1.075 not applicable

TABLE 7J (size 2-0 barbed suture) Ratio of D, L, or Standard P overSuture Measurement Units Average Deviation Diameter (0.381 mm) cut angleθ degrees 161.0 1.506 not applicable cut depth D mm 0.154 0.017 0.40 cutlength L mm 0.474 0.058 1.24 cut distance P mm 0.973 0.068 2.55spirality angle α degrees 6.53 1.755 not applicable

Additional measurements were performed on several other twist cut,multiple spiral, barbed sutures manufactured from monofilament spun frompolydioxanone and having a diameter of about 0.018 inch (about 0.457 mm,which is slightly more than the USP requirement for a size 0 syntheticabsorbable suture) and thus similar to the above-described tested barbedsutures, except that these other barbed sutures were cut with adifferent cutting machine, namely a machine with one blade that movedlongitudinally along the twisted filament between cutting strokes andthat was controlled with a computer to make the various cuts for theescarpment of the barbs. These other barbed sutures were also tested forstraight pull tensile strength and for chamois cloth closure strength.(A discussion of how chamois cloth closure strength is performed can beseen below in connection with FIGS. 13A and 13B.) The results for theseother barbed sutures are summarized in the following Tables 7K-7Z.

TABLE 7K (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 152.6 0.718 not applicable cut depth D mm 0.221 0.011 0.48 cutlength L mm 0.479 0.022 1.05 cut distance P mm 0.784 0.015 1.71spirality angle α degrees 12.9 0.453 not applicable

TABLE 7L (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 152.4 0.947 not applicable cut depth D mm 0.216 0.014 0.47 cutlength L mm 0.465 0.024 1.02 cut distance P mm 0.774 0.015 1.69spirality angle α degrees 13.2 0.349 not applicable

TABLE 7M (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 152.3 0.576 not applicable cut depth D mm 0.227 0.015 0.50 cutlength L mm 0.489 0.034 1.07 cut distance P mm 0.796 0.018 1.74spirality angle α degrees 13.1 0.193 not applicable

TABLE 7N (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 152.8 0.612 not applicable cut depth D mm 0.207 0.007 0.45 cutlength L mm 0.453 0.016 0.99 cut distance P mm 0.798 0.017 1.75spirality angle α degrees 13.6 0.560 not applicable

TABLE 7O (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 152.9 0.549 not applicable cut depth D mm 0.188 0.016 0.41 cutlength L mm 0.413 0.030 0.90 cut distance P mm 0.787 0.024 1.72spirality angle α degrees 13.8 0.270 not applicable

TABLE 7P (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 153.1 0.655 not applicable cut depth D mm 0.204 0.007 0.45 cutlength L mm 0.451 0.019 0.99 cut distance P mm 0.792 0.018 1.73spirality angle α degrees 13.6 0.410 not applicable

TABLE 7Q (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 163.1 0.505 not applicable cut depth D mm 0.245 0.013 0.54 cutlength L mm 0.842 0.045 1.84 cut distance P mm 0.774 0.009 1.69spirality angle α degrees 10.8 0.449 not applicable

TABLE 7R (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 161.1 1.126 not applicable cut depth D mm 0.233 0.017 0.51 cutlength L mm 0.721 0.035 1.58 cut distance P mm 0.773 0.010 1.69spirality angle α degrees 12.6 0.189 not applicable

TABLE 7S (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 160.9 0.708 not applicable cut depth D mm 0.240 0.014 0.52 cutlength L mm 0.734 0.037 1.61 cut distance P mm 0.774 0.009 1.69spirality angle α degrees 13.6 0.312 not applicable

TABLE 7T (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 154.6 1.434 not applicable cut depth D mm 0.210 0.009 0.46 cutlength L mm 0.492 0.026 1.08 cut distance P mm 0.538 0.011 1.18spirality angle α degrees 12.3 0.223 not applicable

TABLE 7U (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 152.9 0.809 not applicable cut depth D mm 0.212 0.014 0.46 cutlength L mm 0.464 0.026 1.01 cut distance P mm 0.530 0.015 1.16spirality angle α degrees 13.7 0.411 not applicable

TABLE 7V (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 153.4 0.903 not applicable cut depth D mm 0.221 0.010 0.48 cutlength L mm 0.495 0.023 1.08 cut distance P mm 0.537 0.012 1.17spirality angle α degrees 13.9 0.605 not applicable

TABLE 7W (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 155.2 0.829 not applicable cut depth D mm 0.202 0.008 0.44 cutlength L mm 0.483 0.017 1.06 cut distance P mm 0.789 0.031 1.73spirality angle α degrees 12.6 0.328 not applicable

TABLE 7X (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 155.5 0.799 not applicable cut depth D mm 0.200 0.010 0.44 cutlength L mm 0.484 0.027 1.06 cut distance P mm 0.798 0.017 1.75spirality angle α degrees 11.8 0.362 not applicable

TABLE 7Y (size 0 barbed suture) Ratio of D, L, or Standard P over SutureMeasurement Units Average Deviation Diameter (0.457 mm) cut angle θdegrees 155.4 0.560 not applicable cut depth D mm 0.196 0.008 0.43 cutlength L mm 0.471 0.017 1.03 cut distance P mm 0.799 0.019 1.75spirality angle α degrees 11.8 0.496 not applicable

TABLE 7Z Straight Chamois Cloth Pull Strength Closure Strength BarbedSuture (pounds) (pounds to rupture) Sample 1 (Tables 7K-7M) 7.29 11.23Sample 2 (Tables 7N-7P) 8.73 12.14 Sample 3 (Tables 7Q-7S) 8.5 9.22Sample 4 (Tables 7T-7V) 5.92 9.27 Sample 5 (Tables 7W-7Y) 7.69 9.97

Although all the above-noted measurements were performed onbi-directional, twist cut, multiple spiral barbed sutures, thebelow-noted desirable ranges for measurements for barb length L, barbcut depth D, barb cut angle θ, and/or cut distance P should be the samefor the various other inventive barbed sutures described here.

A suitable ratio of cut length L to barbed suture diameter SD rangesfrom about 0.2 to about 2, more preferably from about 0.4 to about 1.7,even more preferably from about 0.8 to about 1.5. However, very suitablebarbed sutures may have a ratio of cut length L to barbed suturediameter SD from about 1 down to about 0.2, whereby the ratio of thehighest possible barb elevation (the elevation of barb tip 85 abovesuture body 82) to the suture diameter SD correspondingly ranges fromabout 1 down to about 0.2. (The highest possible barb elevation is thesame as the barb length L.) Also, a suitable ratio of cut depth D tobarbed suture diameter SD ranges from about 0.05 to about 0.6, morepreferably from about 0.1 to about 0.55, even more preferably from about0.2 to about 0.5.

Regardless, length L may be desirably varied depending on the intendedend use, since larger barbs are more suitable for joining certain typesof tissue such as fat tissue or soft tissue, whereas smaller barbs aremore suitable for joining other types of tissues such as fibrous tissue.As discussed in more detail below vis-à-vis FIG. 11, there will also beinstances where a barb configuration that is a combination of large,medium, and/or small barbs disposed on the same suture will bedesirable, for instance, when the barbed suture is employed in tissuethat has differing layer structures.

Cut angle θ formed between the barb and the elongated suture bodydesirably would range from about 140 degrees to about 175 degrees, morepreferably would range from about 145 degrees to about 173 degrees. Themost preferred cut angle θ for all barbs ranges from about 150° to about170°.

For instance, for a polydioxanone barbed suture with a diameter of about0.018 inch (about 0.457 mm), which is slightly larger that the USPrequirement for a synthetic absorbable suture of size 0, the preferredbarb length L would be 0.45 mm; the preferred barb depth D would be 0.2mm; and the preferred barb cut angle would be 153 degrees.

Longitudinal spacing between any two barbs is generally effected withthe goal of creating as many barbs as possible along the suture, and isa factor in the ability of the barbed suture to anchor tissues whilemaintaining firmness. As barbs are spaced farther apart,tissue-anchoring capacity decreases. Nevertheless, if barbs are spacedtoo close, the integrity of the filament may be jeopardized, which couldlead to a tendency of the barbs to peel back and also to a decrease insuture tensile strength.

Generally, a suitable ratio of cut distance P to barbed suture diameterSD ranges from about 0.1 to about 6, more preferably from about 0.5 toabout 4.5, even more preferably from about 1.0 to about 3.5. Verysuitable barbed sutures may have a ratio of cut distance P to barbedsuture diameter SD from about 1.5 down to about 0.2, whereby cutdistance P may be as low as about 0.1, particularly for the overlappingbarb embodiment, which is discussed in more detail below vis-à-vis FIGS.12A, 12B, 12C, and 12D.

Additionally, spirality angle α formed between line M and thelongitudinal direction of the elongated suture body for a twist cut,multiple spiral barbed suture typically would range from about 5 degreesto about 25 degrees, more preferably from about 7 degrees to about 21degrees. The most preferred angle α for all barbs on a twist cut,multiple spiral barbed suture is about 10° to about 18°.

Turning now to FIG. 8, shown is suture 90, which is another embodimentof the present invention. Suture 90 includes elongated body 92 that isgenerally circular in cross section. Elongated body 92 terminates infirst and second pointed ends 94, 96 for penetrating tissue. It iscontemplated that one or both ends 94, 96 may comprise a surgical needle(not shown) for insertion into tissue. Additionally, suture 90 includesplurality of closely spaced barbs 97 arranged in a random disposition.

Suture 90 may be made with the same cutting machine as theabove-discussed sutures, such as the cutting device described in theabove-noted Ser. No. 09/943,733 to Genova et al. With combinations ofthe above-described methods for making the 180 degree disposition(sutures 1, 10), the 120 degree disposition (sutures 30, 40), and/or thetwist cut multiple spiral disposition (sutures 60, 70, 80), barbedsuture 90 with a very random barb disposition is obtained. The advantageof the random disposition is that the many barb angles provide superioranchoring in tissues and thus afford superior wound holding properties.With the random disposition, the barbed suture would be inserted intotissue with an insertion device, such as that shown in the above-notedU.S. Pat. No. 5,342,376 to Ruff.

With regard to FIG. 9, shown is a sectional side view of barbed suture100, which is another embodiment of the present invention. Suture 100includes elongated suture body 102 of generally circular cross section.Also, suture body 102 has disposed on it a plurality of closely spacedbarbs 107. Each barb 107 has a barb configuration such that barbunderside 108 is serrated or corrugated. One or both suture ends (notshown) are pointed for penetrating tissue and it is contemplated thatone or both may comprise a surgical needle (not shown) for insertioninto tissue.

Suture 100 may be made with the same cutting machine as theabove-discussed sutures, such as the cutting device described in theabove-noted Ser. No. 09/943,733 to Genova et al. Barb 107 havingserrated underside 108 is achieved by vibrating or oscillating thecutting blades of the cutting device when barbs are being escarped intothe body of a monofilament. It is intended that any of the barbedsutures of the present invention as described here may have barbs with aconfiguration that includes a serrated or corrugated underside.

With reference now to FIGS. 10A and 10B, depicted in FIG. 10A is aperspective view and depicted in FIG. 10B is a top view of barbed suture110, which is another embodiment of the present invention. Suture 110includes elongated suture body 112 of generally circular cross section.Also, suture body 112 has disposed on it a plurality of closely spacedbarbs 115 having barb tips 117 (one barb 115 is shown for purposes ofbrevity). Barb 115 has a configuration with an arcuate base 119 wherebarb 115 is attached to suture body 112. One or both suture ends (notshown) are pointed for penetrating tissue and it is contemplated thatone or both may comprise a surgical needle (not shown) for insertioninto tissue.

FIGS. 10C and 10D are cross-sectional views respectively along line10C-10C and line 10D-10D of FIG. 10B. FIGS. 10C and 10D further clarifythat barb 115 becomes narrower going from base 119 toward tip 117.

Suture 110 may be made with the same cutting machine as theabove-discussed sutures, such as the cutting device described in theabove-noted Ser. No. 09/943,733 to Genova et al. To achieve barb 115having arcuate base 119, the cutting device is provided with cuttingblades with ends that are correspondingly arcuate with respect toarcuate base 119.

It is intended that any of the barbed sutures of the present inventionas described here may have barbs with a configuration that includes anarcuate base. The arcuate base should enhance tissue anchoring ascompared to a flat, linear base. Regardless, it is not desired for thebase to be circular or oval, which would result from conical shapedbarbs, as that could decrease tissue anchoring.

Shown in FIG. 11 is a sectional side view of a barbed suture that isanother embodiment of the present invention, and that is generallydesignated at 120. Suture 120 includes elongated body 122 that isgenerally circular in cross section. Elongated body 122 terminates inend 124. End 124 is pointed for penetrating tissue and it iscontemplated that end 124 may comprise a surgical needle (not shown) forinsertion into tissue. (The other end is not shown, and also may bepointed for penetrating tissue and may comprise a surgical needle forpenetrating tissue.) Also, suture 120 includes plurality of closelyspaced barbs 125, plurality of closely spaced barbs 127, and pluralityof closely spaced barbs 129. Barbs 125 are relatively small in size witha relatively short barb length as compared to barbs 127, which arerelatively medium in size with a relatively medium barb length, ascompared to barbs 129, which are relatively large in size with arelatively long barb length.

Suture 120 may be made with the same cutting machine as theabove-described sutures were made, such as the cutting device describedin the above-noted Ser. No. 09/943,733 to Genova et al. By altering theamount of blade movement during cutting into a suture filament, then thebarb cut length is made longer or shorter, as desired, to result in eachof the three sets of barbs 125, 127, and 129 being of a size differentfrom the others, where the varying sizes are designed for varioussurgical applications. The barb size may also vary in the transversedirection, whereby the barb base may be short, medium, or long, andregardless, the barb base typically is less than about ¼ of the suturediameter.

For instance, relatively larger barbs are desirable for joining fat andsoft tissues, whereas relatively smaller barbs are desirable for joiningfibrous tissues. Use of a combination of large, medium, and/or smallbarbs on the same suture helps to ensure maximum anchoring propertieswhen barb sizes are customized for each tissue layer. Only two differentsized sets of barbs (not shown) may be escarped into suture body 122, oradditional sets of barbs (not shown) with four, five, six, or moredifferent sized sets than three sizes as illustrated for sets of barbs125, 127, and 129 may be escarped into suture body 122 as desired, inaccordance with the intended end use. Also, although suture 120 isillustrated with the barbs being unidirectional, it is intended thatbarbed sutures with barbs having a configuration of varying sizes inaccordance with the invention also may be bi-directional barbed suturesor random barbed sutures or any of the other inventive barbed suturesdescribed here.

FIG. 12A is a perspective view of another embodiment of the presentinvention, showing barbed suture 130 having elongated body 132 ofgenerally circular cross section. One or both suture ends (not shown)are pointed for penetrating tissue and it is contemplated that one orboth ends may comprise a surgical needle (not shown) for insertion intotissue.

Suture 130 further includes plurality of barbs 135 projecting from body132 such that at least two longitudinally adjacent first and secondbarbs 135 are disposed on body 132 where first barb 135 overlaps secondbarb 135 if first and second barbs 135, which is readily apparent ifbarbs 135 are laid flat on body 132.

FIG. 12B is a perspective view of a portion of overlapping barbs 135 ofthe overlapping disposition barbed suture 130 of FIG. 12A, and FIG. 12Cis a top plan view of FIG. 12B. FIG. 12D is a cross-sectional view alongling 12D-12D of FIG. 12C. As can be more clearly seen from FIGS. 12B,12C, and 12D, during escarpment of barbs 135, overlapping first barb 135is escarped into part of topside TS of overlapped second barb 135, andso on. Part of topside TS of overlapped second barb 135 becomes part ofunderside US of overlapping first barb 135.

Thus, with the overlapping disposition, the barb cut distance betweenfirst barb 135 and second barb 135 may be shorter than the barb cutlength of overlapped second barb 135, whereas, in general for barbedsutures, the barb cut distance between two barbs>the barb cut length.Particularly for the overlapping barb disposition, very suitable barbedsutures may have a ratio of the barb cut distance to the barbed suturediameter from about 1.5 down to about 0.2, since the barb cut distance Pmay be as low as about 0.1. (See discussion of FIG. 7 for commentsvis-à-vis the barb cut length and the barb cut distance.) Thisoverlapping disposition allows for closely packing many barbs 135 onbody 132, and typically, barbs 135 are thin, as compared to when thebarb cut distance between two barbs>the barb cut length.

Also, although suture 130 is illustrated with barbs 135 beingunidirectional, it is intended to include that suture 130 in accordancewith the invention also may be a bi-directional barbed suture asdescribed here.

FIGS. 13A, 13B, 13C, and 13D show various surgical needles, where abarbed suture is attached to each surgical needle. In order tofacilitate insertion into tissue, the surgical needles may be coatedwith a polymer, for instance, as described above vis-à-vis U.S. Pat. No.5,258,013 to Granger et al.

FIG. 13A shows surgical needle N1 that is a straight elongated needle inthe longitudinal direction and that is generally circular in crosssection. Surgical needle N1 has pointed tip T1 for insertion into tissueand also has hole H1. Surgical needle N1 is illustrated as attached,such as by swaging, to barbed suture S1. Barbed suture Si is a barbedsuture including, but not limited to, any of the above-described barbedsutures. Additionally, surgical needle N1 has diameter D1 in thetransverse direction, which is illustrated as a relatively thindiameter, such as about 0.02 inch (about 0.51 mm). As discussed abovevis-à-vis swaging, surgical needle N1, after having suture S1 insertedinto hole H1, may be crimped by standard procedures about hole H1 tohold suture S1 in place for suturing tissue.

FIG. 13B shows surgical needle N2 that is a straight elongated needle inthe longitudinal direction and that is generally circular in crosssection. Surgical needle N2 has pointed tip T2 for insertion into tissueand also has hole H2. Surgical needle N2 is illustrated as attached,such as by swaging, to barbed suture S2. Barbed suture S2 is a barbedsuture including, but not limited to, any of the above-described barbedsutures. Additionally, surgical needle N2 has diameter D2 in thetransverse direction, which is illustrated as a suitably thin diameter,such as about 0.032 inch (about 0.81 mm), but not as thin as diameter D1of surgical needle N1. As discussed above vis-à-vis swaging, surgicalneedle N2, after having suture S2 inserted into hole H2, may be crimpedby standard procedures about hole H2 to hold suture S2 in place for usein suturing tissue.

FIG. 13C shows surgical needle N3 that is a curved elongated needle inthe longitudinal direction and that is generally circular in crosssection. Surgical needle N3 has pointed tip T3 for insertion into tissueand also has hole H3. Surgical needle N3 is illustrated as attached,such as by swaging, to barbed suture S3. Barbed suture S3 is a barbedsuture including, but not limited to, any of the above-described barbedsutures. Additionally, surgical needle N3 has diameter D3 in thetransverse direction, which is illustrated as a relatively thindiameter, such as about 0.02 inch (about 0.51 mm) As discussed abovevis-à-vis swaging, surgical needle N3, after having suture S3 insertedinto hole H3, may be crimped by standard procedures about hole H3 tohold suture S3 in place for use in suturing tissue.

FIG. 13D shows surgical needle N4 that is a curved elongated needle inthe longitudinal direction and that is generally circular in crosssection. Surgical needle N4 has pointed tip T4 for insertion into tissueand also has hole H4. Surgical needle N4 is illustrated as attached,such as by swaging, to barbed suture S4. Barbed suture S4 is a barbedsuture including, but not limited to, any of the above-described barbedsutures. Additionally, surgical needle N4 has diameter D4 in thetransverse direction, which is illustrated as a suitably thin diameter,such as about 0.032 inch (about 0.81 mm), but not as thin as diameter D3of surgical needle N3. As discussed above vis-à-vis swaging, surgicalneedle N4, after having suture S4 inserted into hole H4, may be crimpedby standard procedures about hole H4 to hold suture S4 in place for usein suturing tissue.

Needle tips T1, T2, T3, and T4 are schematically illustrated as pointed,but, as is well known, surgical needles come with various kinds ofpointed tips, such as taper point, taper cutting, ball point, cuttingedge, diamond point, thin line, and lancet point, and it is intended toinclude, but not be limited to, all such needle tips. Taper point, tapercutting, and diamond point are preferred needle tips for surgicalneedles used with barbed sutures.

As is well known in the art, needle diameter for surgical needles usedwith conventional (i.e., unbarbed) sutures is considered unimportant,and often very thick surgical needles are used with thin conventionalsutures such that the ratio of surgical needle diameter to conventionalsuture diameter is 4:1 or even higher, such as 4.43:1.

However, with the surgical needle/barbed suture combination of thepresent invention (for either a straight needle or a curved needle), thethinner that the surgical needle is, then the more preferable that thesurgical needle/barbed suture is, with the desired needle diameter beingthinner and thinner as it approaches the barbed suture diameter, and itis possible that the needle diameter may be even thinner than the barbedsuture diameter.

In general for the present invention, a relatively thin surgical needleattached to a barbed suture is more preferable for approximating tissuewhen stitching a wound closed than a relatively thick surgical needlethreaded with a barbed suture. The reason is that the relatively thinsurgical needle attached to a barbed suture allows for greaterengagement of barbs in tissue, and therefore provides better closurestrength to the approximated tissue that has been sutured to prevent theopposing sides of the closed wound from pulling apart, as compared tothe closure strength provided to approximated tissue that has beensutured with the relatively thick surgical needle.

The most important feature for the combination of the surgical needleattached to the barbed suture is that the surgical needle diametershould be of sufficient width in order to make a hole or a channel inthe end, such by drilling, to allow for insertion of the barbed sutureinto the hole or the channel. Nevertheless, as the surgical needlediameter increases, the surgical needle is still suitable as long as theratio of the surgical needle diameter to the barbed suture diameter isabout 3:1 or less.

Accordingly, a desirable ratio of surgical needle diameter to barbedsuture diameter, for either a straight needle or a curved needle, isabout 3:1 or less, more preferably about 2:1 or less, most preferablyabout 1.8:1 or less. Furthermore, particularly if channel needles areemployed, the ratio of surgical needle diameter to barbed suturediameter may be as low as about 1:1 or less, or even lower; forinstance, about 0.9:1 or less, or about 08:1 or less, or as low as about0.5:1. It will be appreciated by the person of ordinary skill in the artthat care should be taken with extremely thin needles so as toameliorate the possibility of localized weakness, which may compromisetissue insertion.

Closure strength of thin surgical needles, both having a ratio ofsurgical needle diameter to barbed suture diameter suitable for thepresent invention, was tested as follows.

Various pieces of chamois leather (manufactured by U.S. Chamois ofFlorida) having a thickness of about 0.6 in (about 15.2 mm) were cutwith a wound having a length of about 1.25 inch (about 32 mm).

A first specimen was made from a piece of chamois leather by stitchingtogether the respective edges of the wound with a drilled end surgicalneedle (item no. 382077A purchased from Sulzle Company) which was swagedwith a barbed suture. In other words, after insertion of the barbedsuture into the needle hole, the needle was crimped about the hole tosecure the barbed suture during stitching. After stitching closed thewound, the piece of chamois leather was cut to a rectangular shape ofabout 3 inches (about 76 mm) in length by about 1.25 inches (about 32mm) in width, where the stitched wound was in the middle of the lengthand transverse the width. The needle was a taper point, curved surgicalneedle (⅜ of a circle), with a length of about 22 mm and a relativelythin diameter of about 0.020 inch (about 0.51 mm)

Then, using the same stitching method, a second specimen was made fromanother piece of chamois leather by stitching together the respectiveedges of the wound, using a drilled end surgical needle (item no.383271A purchased from Sulzle Company) swaged with the same kind ofbarbed suture, i.e., the surgical needle was crimped about the needlehole, after insertion of the barbed suture into the hole, to secure thebarbed suture during stitching. For the second specimen, the needle wasa taper point curved surgical needle (⅜ of a circle) with a length ofabout 22 mm and a suitable thin diameter of about 0.032 inch (about 0.81mm), although not as thin as the diameter of the needle used for firstspecimen.

Each barbed suture for each specimen was a bi-directional, twist cutmultiple spiral, polydioxanone barbed suture like suture 70 in FIG. 6A,except that each barbed suture had a diameter of about 0.0115 inch(about 0.291 mm, which is slightly larger than the USP requirement for asize 3-0 synthetic absorbable suture), instead of a suture diameter ofabout 0.018 inch (about 0.457 mm).

Both the first and the second specimens of stitched chamois cloth weretested for closure strength using a Test Resources Universal Tester,Model 200Q. Each specimen was gripped by two respective serrated jaws.Then, each specimen was pulled longitudinally at a rate of about 10inches per minute (about 254 mm per minute) until complete rupture. Thepeak load in pounds reached before complete wound disruption wasrecorded as the closure strength. The results were that the firstspecimen (which was sutured with the needle that had a relatively thindiameter of about 0.020 inch, about 0.51 mm) took 5.88 pounds untilwound disruption occurred and the specimen pulled apart back into 2pieces, whereas the second specimen (which was stitched with the needlethat had a suitably thin diameter of about 0.032 inch, about 0.81 mm,but not as thin as the needle for the first specimen) took only 2.88pounds until the wound disruption and the specimen pulled apart backinto 2 pieces.

The results are summarized in Table 13A below.

TABLE 13A (Chamois Cloth Closure Strength) Needle Barbed Suture Poundsto Specimen Diameter Diameter Ratio* Rupture First 0.020 inch 0.0115inch 1.74 5.88 Second 0.032 inch 0.0115 inch 2.78 2.88 *Ratio ofsurgical needle diameter to barbed suture diameter.

Also, various pieces of rat skin were cut and stitched for testing ofmore surgical needles swaged with barbed sutures as follows.

Three freshly killed Sprague-Dawley rats, each about 600 to 700 g, wereused. Two full-thickness skin incisions were made on the back of eachrat to create wounds. Each wound was about 4 cm in length and parallelto the spine.

For each rat, one of the two wounds was closed with a drilled end,curved surgical needle that was a Sulzle item no. 382273A, which was ⅜circle. The needle had a length of 18 mm and a diameter of about 0.022inch (about 0.56 mm) Also, the needle had a taper point needle tip wherethe needle tip had been ground to a 3-facet cut to approximate a tapercutting needle tip to facilitate penetration of rat tissue. The needlewas swaged to a barbed suture.

The other of the two wounds was closed using the same suturingtechnique, but with a drilled end, curved surgical needle that was aSulzle item no. 832679A, which was ⅜ circle. The needle had a length ofabout 18 mm and a diameter of about 0.026 inch (about 0.66 mm) Also, theneedle had a diamond point needle tip. The needle was swaged to a barbedsuture.

Each barbed suture for each specimen was a bidirectional, twist cutmultiple spiral, polydioxanone barbed suture like suture 70 in FIG. 6A,except that each barbed suture had a diameter of about 0.015 inch (about0.381 mm, which is slightly larger than the USP requirement for a size2-0 synthetic absorbable suture), instead of a suture diameter of about0.018 inch (about 0.457 mm).

For each stitched wound, a tissue specimen that was approximately asquare measuring about 4 cm×about 4 cm, with the stitched wound in themiddle paralleling two opposing tissue edges, was retrieved for closurestrength testing.

The force to open each wound was determined using a Test ResourcesUniversal Tester, Model 200Q. For each tissue specimen, the two edgesparalleling each stitched wound were mounted in the two respectiveserrated jaws of the tester.

Then, each specimen was pulled longitudinally at a rate of about 2inches per minute (about 51 mm per minute) until complete ruptureoccurred. The maximum force encountered before complete wound disruptionwas recorded as the closure strength.

The results were averaged from the first set of three wounds closed witha needle having a diameter of about 0.022 inch (about 0.56 mm) andswaged to a barbed suture. Also, the results were averaged from thesecond set of three wounds closed with a needle having a diameter ofabout 0.026 inch (about 0.66 mm) and swaged to a barbed suture.

The results are summarized in Table 13B below.

TABLE 13B (Rat Skin Closure Strength) Average of 3 Wounds Needle BarbedSuture Pounds to Specimens Diameter Diameter Ratio* Rupture First set of3 0.022 inch 0.015 inch 1.47 11.9 Second set of 3 0.026 inch 0.015 inch1.73 8.1 *Ratio of surgical needle diameter to barbed suture diameter.

Thus, the lower the ratio of surgical needle diameter to barbed suturediameter, then the better the closure strength when suturing a woundclosed with a surgical needle attached to a barbed suture. In general,the thinner the surgical needle, the better the closure strength,particularly for delicate tissues; however, for tough tissues, such asmuscle and bowel, thicker needles are preferred. Thus, what isimportant, regardless of whether the needle is thick or thin orsomewhere in the middle, is that the ratio of surgical needle diameterto barbed suture diameter should be about 3:1 or less, more preferablyabout 2:1 or less.

Although the present invention has been shown and described in detailwith regard to only a few exemplary embodiments of the invention, itshould be understood by those skilled in the art that it is not intendedto limit the invention to the specific embodiments disclosed. Variousmodifications, omissions, and additions may be made to the disclosedembodiments without materially departing from the novel teachings andadvantages of the invention, particularly in light of the foregoingteachings. For instance, the barbed suture of the present invention canbe used alone or with other closure methods, such as staples and/or skinadhesives, to aid in holding the position of the tissue. Accordingly, itis intended to cover all such modifications, omissions, additions, andequivalents as may be included within the spirit and scope of theinvention as defined by the following claims.

1. A self-retaining suture formed from stock monofilament of abioabsorbable polymer, the stock monofilament having a filament diameter(D) and a tensile strength, wherein the self-retaining suture comprises:a strand of said stock monofilament, the strand having a first end, asecond end, a longitudinal axis, and a surface; a plurality of cuts madeinto the surface of the strand; the plurality of cuts defining aplurality of barbs adapted to permit movement of the strand throughtissue towards the first end and resist movement in an oppositedirection; each barb having a tip separated from the strand and a baseconnected to the strand; each barb having a length no less than about0.8 filament diameters (0.8*D), measured tip-to-base along thelongitudinal axis; adjacent barbs being distributed at a spacing nolarger than two filament diameters (2*D), measured tip-to-tip along thelongitudinal axis; and the self-retaining suture having a tensilestrength no less than about one third of the tensile strength of thestock monofilament from which the self-retaining suture is made.
 2. Theself-retaining suture of claim 1, wherein the spacing between adjacentbarbs is less than about one-and-a-half filament diameters (1.5*D). 3.The self-retaining suture of claim 2, wherein the filament diameter (D)is less than about 1 mm.
 4. The self-retaining suture of claim 3,wherein the spacing between adjacent barbs is less than about 1 mm. 5.The self-retaining suture of claim 4, wherein the filament diameter (D)is less than about 0.5 mm.
 6. The self-retaining suture of claim 1,wherein each barb has a length no less than about one filament diameter(1*D).
 7. The self-retaining suture of claim 1, wherein the plurality ofbarbs includes a first set of barbs, a second set of barbs and a thirdset of barbs, the first set of barbs being radially displaced by 120degrees from the second set of barbs, the third set of barbs beingradially displaced by 120 degrees from first set of barbs and from thesecond set of barbs.
 8. The self-retaining suture of claim 1, whereinthe self-retaining suture has a tensile strength at least substantiallyequivalent to a USP minimum knot pull strength requirement for anunbarbed suture made from the same stock monofilament.
 9. Theself-retaining suture of claim 1, wherein the self-retaining suture hasa tensile strength greater than 7 pounds.
 10. The self-retaining sutureof claim 1, wherein the bio-absorbable polymer is a polymer of at leastone monomer selected from the group consisting of: dioxanone; lactide;glycolide; and caprolactone.
 11. The self-retaining suture of claim 1,wherein the bio-absorbable polymer comprises a copolymer of glycolideand trimethylene carbonate.
 12. The self-retaining suture of claim 1,wherein the tip of each barb is pointed.
 13. A wound-closure deviceformed from stock monofilament of a bioabsorbable polymer, the stockmonofilament being elongate and flexible and having a filament diameter(D) and a tensile strength, wherein the wound-closure device comprises:a strand of said stock monofilament, the strand having a first end, asecond end, a longitudinal axis, and a surface; a plurality of cuts madeinto the surface of the strand; the plurality of cuts defining aplurality of projections adapted to permit movement of the strandthrough tissue towards the first end and resist movement in an oppositedirection; each projection having an apex separated from the strand anda base connected to the strand; each projection having a length no lessthan about 0.8 filament diameters (0.8*D), measured apex-to-base alongthe longitudinal axis; adjacent projections being distributed at aspacing no larger than two filament diameters (2*D), measuredapex-to-apex along the longitudinal axis; and the wound-closure devicehaving a tensile strength no less than about one third of the tensilestrength of the stock monofilament from which the wound-closure deviceis made.
 14. The wound-closure device of claim 13, wherein the pluralityof projections includes a first set of at least thirty projections, asecond set of at least thirty projections and a third set of at leastthirty projections, the first set of at least thirty projections beingradially displaced by 120 degrees from the second set of at least thirtyprojections, the third set of at least thirty projections being radiallydisplaced by 120 degrees from the first set of at least thirtyprojections and from the second set of at least thirty projections. 15.The wound-closure device of claim 13, wherein each projection has alength no less than about one filament diameter (1*D).
 16. Thewound-closure device of claim 13, wherein the wound-closure device has atensile strength at least substantially equivalent to a USP minimum knotpull strength requirement for a suture made, without such projections,from the same stock monofilament.
 17. The wound-closure device of claim13, wherein the wound-closure device has a tensile strength greater thanseven pounds.
 18. The wound-closure device of claim 13, wherein eachapex is pointed.
 19. The wound-closure device of claim 13, wherein eachprojection comprises a barb.
 20. A wound-closure device formed fromstock monofilament of a bioabsorbable polymer, the stock monofilamentbeing elongate and flexible and having a filament diameter (D) less than1 mm, wherein the wound-closure device comprises: a strand of said stockmonofilament, the strand having a first end, a second end, alongitudinal axis, and a surface; a plurality of cuts made into thesurface of the strand; the plurality of cuts defining a plurality ofprojections adapted to permit movement of the strand through tissuetowards the first end and resist movement in an opposite direction; eachprojection having an apex separated from the strand and a base connectedto the strand; each projection having a length no less than about 0.8filament diameters (0.8*D), measured apex-to-base along the longitudinalaxis; adjacent projections being distributed at a spacing no larger thantwo filament diameters (2*D), measured apex-to-apex along thelongitudinal axis; and the wound-closure device having a tensilestrength greater than 7 lbs.